Preheating apparatus



April 22, 1941. P. T. LINDHARD ETAL PREHEA'I ING APPARATUS Filed July16, 1940 2 Sheets-Sheet 1 [III/III) ATTORNEY? April 22, 1941'. P. T.LINDHARD ETAL PREHEATING APPARATUS 2 Sheets-Sheet 2 Filed July l6, 1940\M NM MM ATTORNEY)" Patented Apr. 22, 1941 UNITED STATES PATENT OFFICEPREHEATING APPARATUS Povl T. Lirrdhard, Rumson, and Einar Svendsen,Cranford, N. J., assignors to F. L. Smidth & 00., New York, N. Y., acorporation of New Jersey Appiicatic-n July 16, 1949, Serial No. 345,723

15 Claims.

This invention relates to apparatus for the preheating of materials byhot gases, such, for example, as the exhaust gases from the kiln inwhich the materials are later burned, and more particularly, theinvention has to do with a preheating apparatus which includes a novelgrate or pervious support for the material undergoing treatment.

Preheating apparatus of the type referred to may take various forms andin one such apparatus, disclosed in United States Patent No. 2,024,453,issued December 17, 1935, on an application of Vogel-Jorgensen, thematerial to be preheated is deposited on the surface of a perviouscylindrical support which is mounted within an extension of the shell ofa rotary kiln and rotates with the kiln. The continuously depositedmaterial forms a layer which is held in place on the support by the hotgases from the kiln passing through the layer and support, and after thematerial has been carried through the major portion of a revolution, itis discharged from the support by compressed air and is introduced intothe kiln. Instead of being mounted within an extension of the shell of akiln, the Vogel-Jorgensen preheater may be a separate piece of apparatusconnected to the kiln in such manner that the exhaust gases flowtherefrom to the preheater and the preheated material passes directly tothe kiln.

In either form of the preheater referred to, the support on which thematerial is deposited is subjected to varying temperatures during eachrevolution thereof, since, during a part of a revolution, hot gases passthrough the support and at another point, compressed air flows throughthe support. The support, if made in one piece or several large pieces,may, therefore, warp as a result of expansion and contraction. Thepresent invention is, accordingly, directed to the provision of asupport or grate made up of a plurality of sections which can be readilymounted in position, and the grate and the supporting means therefor areof simple inexpensive construction. The formation of the grate of aplurality of sections overcomes contraction and expansion difficultiesand the new grate can be readily assembled in the initial installationand taken apart for repairs, if necessary.

For a better understanding of the invention, reference may be had to theaccompanying drawings in which Fig. l is a vertical sectional viewthrough a preheating apparatus constructed in accordance with theinvention;

Fig. 2 is a sectional view on the line 2--2 of Fig. 1;

Figs. 3 and 4 are sectional views on the lines 3-3 and 44, respectively,of Fig. 2;

Fig. 5 is a sectional view through one section of the new grate;

Fig. 6 is a fragmentary plan view on the line 56 of Fig. 2 with partsbroken away; and

Fig. 7 is a sectional view on the line 1--'! of Fig. 2.

In the drawings, the grate of the invention is illustrated as mountedwithin an extension ID of the shell ll of a rotary kiln. The shell hasthe usual firebrick lining l2 and between the end of the shell and theextension is a collecting ring [3 provided with ports l4 formed byradial ribs IS. A sectional protecting ring [6 of high temperature metalis mounted within the collecting ring to protect the inner surfacethereof and the extension II], which is of conical formation, is securedto the collecting ring by a flange l1. At its outer end, the extensionis provided with a flange 18 to which is secured a wear ring I9 makingsliding contact with the flange 20 of a stationary hood (not shown)which closes the feed end of the kiln.

Mounted on the inner face of the extension l0 and extending lengthwisethereof in alignment with the partitions l5 are ribs 2|, each rib beingformed of a group of three sections, each of which is secured to thewall of the extension by cap screws 22 which pass through that wall andenter bosses 23 formed integrally with the rib sections. Along theirouter edges, the rib sections are provided with flanges 24 engaging theinner surface of the wall of the extension and the ends of adjacentsections are provided with a slot and rib connection, generallydesignated 25 (Fig. 7), to permit relative expansion. The end 26 of theend section 2| a of each rib is received in a vertical slot 21 in thealigned partition [5 in the collector ring [3 and at the other end ofthe extension I0, a sectional ring 28 is secured to the inner face ofthe extension and'has notches 29 for receiving the adjacent ends of ribsections Zlb. To prevent gas leakage, the under surface of the flange 24isprovided with a space for the reception of packing 3H and packing mayalso be introduced in the slots of the expansion connections 25 and inthe notches 21 and 29.

Although the extension is frusto-conical in shape, the formation of eachrib is such that its ree edge lies in a plane and along that edge is anintegral flange 3| which is cut away at spaced points, as indicatedat32. Inward from each cutout, the rib is stifiened by a short rib 33. Ifdesired, the ribs may be provided with T-bars 34 bolted or otherwisesecured thereto instead of being formed with the integral flangesdescribed.

The grate is made up of a plurality of sections, each of which consistsof a plurality of flat bars 35 extending vertically and having crossbars36 securedto the upper edges thereof by welding. The crossbars arepreferably round in section and they lie spaced apart a suitabledistance to permit the passage of the gases between them. The outer fiatbars 35a are provided with outwardly projecting pins 31 which extendparallel to the crossbars 36 and lie below them a suitable dis-' tance,the outer ends of the pins lying inward from the ends of the crossbars.

In mounting the grate sections on the ribs, the sections are lowered inplace against the outer edges of the ribs, with the pins passing throughthe cut-outs 32 in the flanges 3! or in the upper ends of the T--bars34. Thereafter, the grate sections are moved endwise so that the pinsare out of registry with the notches. The length of the grate sectionsis such that there are a number' of sections in lengthwise alignmentclosing the space between adjacent ribs, and in the construction shown,six grate sections are required for the purpose, although the numberwill vary'with different installations. When all of the sections are inplace, they are held against endwise movement which would bring theirpins in alignment with the cutouts '32 by means of key pieces 38. Eachkey piece is inserted at the end of a row of sections and its endsoverlie the ribs on which the row of sections is mounted. The key pieceis provided with a stud bolt 39 which passes through the Wall'of theextension and a nut 40, threaded on the exposed end of the bolt, servesto hold the key piece in place in tight contact with the ribs which itengages.

In the completed grate, the sections are not rigidlysecured in' placeand may move slightly relative to one another both longitudinally andtransversely. Expansion and contraction, therefore, do not cause bindingthat would producewarping.

Inside the extension at its outer end is mounted-a sectional ring 4|provided with flights 2. This ring is made of heat-resistant materialand has bosses through which bolts 43 may be threaded into the ring 28to hold the sectional ring in place. The flights 42 are inclined so astoprevent material deposited on the grate from escaping out the smallend of the extension and the inner end portions 44 of the flightsare-removed to permit a device for cleaning the grate to be passedbetween them.

As illustrated in Fig. 1, the material is deposited on the inner surfaceof the grate by a distributor 45 which may be of any suitableconstruction, as, for example, that disclosed in the co-pen dingapplication of Vogel-Jorgensen Serial No. 192,257, filed February 24,1938. The layer of material on the grate is held in place by hot gaseswhich issue from the kiln and pass through the layer and grate into thepassages between adjacent ribs, whence the gases flow to the ports M. Amantle 46 encloses the collector ring and the gases are withdrawnthrough the ports and mantle by a fan (not shown) connected to a duct41.

The material on the grate overlying each passage between a pair of ribsremains in position until the port in the collector ring connected tothat passage comes into alignment with the end of an air pipe 48extending through the wall of the mantle and terminating close to theouter ends of the ports. sages successively from the pipe flows alongthe passages and through the grate and causes the material thereon to bedischarged into the trough of a screw conveyor 49 which carries thematerial forward and discharges it into the kiln. The conveyor anddistributor are both protected from contact wi h the hot gases from thekiln by a partition 56 lying within the extension.

As pointed out above, the V ogel-J orgensen type of preheater mayinclude a pervious support mounted within an extension of the shell of arotary kiln, or the support may be part of a separate piece ofapparatus. Also, the support may be arranged so that the material isdeposited on the inner surface thereof and held in place by gasespassing outwardly, or the'material may be deposited on the outer surfaceof the support and held in place by gases flowing inwardly. The grate ofthe invention is suitable for use in any of the types of apparatusreferred to and the changes required to adapt the grate for use in thattype of equipment in which the material is deposited on the outersurface of the support will be readily apparent.

We claim: 7

1. In a preheat-er, means for supporting a layer of material while hotgases pass through it, which comprises a pair of ribs lying side by sideand having free edges, the ribs having lateral extensions formed withspaced cut-outs, a support for the ribs, a grate member resting on theribs and having projections underlying the extensions, and a key pieceat the end of the member preventing endwise movement thereof suificientto bring the projections thereof into line with the cut-outs.

2. In a preheater, means forsupporting a layer of material while hotgases pass through it,

which comprises a pair of ribs lying side by side and having free edgesprovided with flanges having spaced cut-outs, .a support for the ribs, agrate member resting on the flanges of the ribs and having projectionsunderlying the. extensions, and a key piece at the end of the memberpreventing endwise movement thereof sufficient to bring the projectionsthereof into line with the cut-outs.

3. In a preheater, means for supporting a layer of material while hotgases pass through it, which comprises a plurality of ribs mounted sideby side radially in an endless series and having free edges, the ribshaving lateral extensions formed with spaced cutouts, a'suppor't for theribs, grate members spanning the spaces between adjacent ribs, eachmember'having projections underlying the extensions, and key pieces atthe ends of the spaces for preventing .endwise movement of the memberssuflicient to bring the projections thereof into line with the cut-outs.

4. In a preheater, means for supporting a layer of material while hotgases pass through it, which comprises a plurality of ribs mounted sideby side radially in an endless-series and having free edges providedwith flanges having spaced cut-outs, a support for the ribs, gratemembers spanning the spaces between adjacent ribs and resting on theflanges thereofleach member having projections underlying the flanges,and key pieces at the ends of the spaces for preventing endwise movementof the members sufficient to Air introduced into the pasthereof intoline with the which comprises a plurality of ribs mounted side by sideradially in an endless series and having free edges provided withflanges having spaced cut-outs, a support for the ribs, a plurality ofgrate sections spanning each space between ad jacent ribs, the sectionslying in endwise alignment and resting on the rib flanges, each sectionhaving projections underlying the flanges of said ribs, and a key pieceat the end of the group of sections between each pair of adjacent ribsfor preventing endwise movement of the sections suflicient to bring theprojections thereof into alignment with the cut-outs.

6. In a preheater, means for supporting a layer of material while hotgases pass through it, which comprises a drum-like support, a pluralityof ribs mounted on the support side by side and extending generallyradially, each rib having a free edge provided with a flange havingspacedcut-outs, grate members spanning the spaces between adjacent ribs,each member having lateral projections underlying the flanges of saidribs, and key pieces at the ends of the spaces for preventing endwisemovement of the members sufficient to bring the projections thereof intoline with the cut-outs.

7. In a preheater, means for supporting a layer of material while hotgases pass through it, which comprises a plurality of ribs mounted sideby side radially in an endless series and having free edges providedwith flanges having cutouts, a support for the ribs, grate membersresting on the flanges of adjacent ribs and spanning the spaces betweensaid ribs, each member having lateral projections underlying theflanges, key pieces at the ends of the spaces for preventing endwisemovement of the members suflicient to bring the projections thereof intoline with the cut-outs, means for distributing material to be treated onsaid grate members, and means for introducing air into the spacesbetween adjacent ribs to discharge the material from said members.

8. In a preheater, means for supporting a layer of material while hotgases pass through it, which comprises a drum-like support, a pluralityof ribs secured to the surface of the support and extending lengthwisethereof, said ribs and support defining passages extendinglongitudinally of the support and the ribs having free edges providedwith flanges having spaced cutouts, grate members mounted on the ribsand forming perforate walls closing the passages,

said members having lateral projections underlying the flanges, keypieces adjacent one end of the support for preventing endwise movementof the grate members sufficient to bring the projections thereof intoline with the cut-outs, means for distributing material to be treated onthe surface of the grate members, and means for removing the treatedmaterial from said grate members.

9. In a preheat-er, means for supporting a layer of material while hotgases pass through it, which comprises a drum-like support, a pluralityof ribs mounted on said support and extending side by side lengthwisethereof, each rib bein made up of sections with adjacent sections havinginterlocking ends, the ribs having free edges provided with flangeshaving spaced cutouts, a plurality of grate members mounted in endwisealignment to span the spaces between adjacent ribs, said grate membershaving lateral projections underlying the flanges, a pair of rings oneat each end of the group of rings, the rings having notches in which theends of the ribs are received, and a key piece in each space betweenadjacent ribs for preventing the members spanning said space from movingendwise sufficiently to bring the projections thereof into line with thecut-outs.

10. The combination with a rotary kiln having an extension at the inletend thereof of a preheater for the materials to be fed into said kiln,said preheater including a plurality f ribs mounted on said extensionand extending lengthwise thereofleach rib having a free edge providedwith a flange having spaced cut-outs, a pluralityof grate membersmounted on the ribs and having portions resting on the flanges thereofand projections underlying said flanges, and means holding the gratemembers against endwise movement sufficient to bring the projectionsthereof into line with the cut-outs.

11. The combination with a rotary kiln having an extension at the inletend thereof of a preheater for the materials to be fed into said kiln,said preheater including a plurality of ribs mounted on said extensionand extending lengthwise thereof, each rib having a free edge providedwith a flange having spaced cut-outs, a plurality of grate membersmounted on the ribs and having portions resting on the flanges thereofand projections underlying said flanges, means holding the grate membersagainst endwise movement sufficient to bring the projections thereofinto line with the cut-outs, means for distributing material on thesurface of said grate members, and means for removing said materialafter it has traveled part of a revolution of the extension with thekiln.

12. The combination with a rotary kiln having an extension at the inletend thereof of a preheater for the materials to be fed into said kiln,said preheater including a plurality of ribs mounted on said extensionand extending lengthwise thereof, each rib having a free edge providedwith a flange having spaced cut-outs, a plurality of grate membersmounted on the ribs and having portions resting on the flanges thereofand projections underlying said flanges, means holding the grate membersagainst endwise movement sufficient to bring the projections thereofinto line with the cut-outs, means for distributing material on thesurface of said grate members, means for removing said material after ithas travelled part of a revolution of the extension with the kiln, andmeans at the free end of the extension for preventing loss of materialfrom the grate members through said end.

13. The combination with a rotary kiln having an extension at the inletend thereof of a preheater for the materials to be fed into the kiln,which comprises a collector ring disposed between the end of the kilnshell and the extension and having a plurality of ports, a plurality ofribs mounted on the extension in line with the walls of said ports andextending lengthwise of the extension, the ribs having free edgesprovided with flanges having cut-outs, grate members spanning the spacesbetween adjacent ribs and having projections underlying the flanges onsaid ribs, means mounted on the extension for preventing endwisemovement of the grate members suflicient to bring their projections intoline with the cut-outs, means for distributing material on the surfaceof the grate members, the hot gases from the kiln flowing through the.material and members and through the spaces between the ribs to escapethrough said ports, and means for introducing air through the ports intothe spaces between the ribs, the air flowing through the grate memberstodischarge the mater-ial thereon.

14. In a preheater, the combination of a plurality of ribs lying side byside and having free edges provided with flanges having cut-outs,

grate members spanning the spaces between adjacent ribs, each memberincluding longitudinal bars having lateral projections underlying theflanges on said ribs and crossbarsv secured to the longitudinal bars andhaving ends resting on the flanges, and means between adjacent ribs forpreventing endwise movement of the grate flanges on said ribs andcrossbars secured to the longitudinal bars and having ends resting onthe flanges, and key pieces mounted between adjacent ribs, the keypieces having portions engageable by the grate members to preventendwise movement thereof sufilcient to bring their projections into linewith the cut-outs.

POVL T. LINDHARD. EINAR SVENDSEN.

